This section provides background information related to the present disclosure, which is not necessarily prior art.
Vehicles are known to include a heating, ventilation, and air conditioning (“HVAC”) system to improve the comfort of the people within the passenger compartment of the vehicle. The HVAC system can heat and cool air blown through the HVAC system using a heating heat exchanger and/or a cooling heat exchanger. The heating heat exchanger, or heater core typically utilizes the engine coolant as a source of heat for heating the air. The cooling heat exchanger is typically an evaporator which is part of an air conditioning system in the vehicle.
Vehicle HVAC systems typically have internal passages, or ducts for routing air through various components of the system, such as the evaporator, or the heater core for example, before the air is expelled into the passenger compartment. These ducts can also route the air to different locations in the vehicle, such as to be directed toward the left, right, front, or rear of the vehicle for example.
Generally, HVAC systems can include doors, or gates within these ducts, that can be moved between opened and closed positions to selectively control airflow through the individual ducts. The position of these doors can be generally controlled by devices, such as servo motors, or linear actuators. It can be desirable to selectively control the operation of more than one of these doors simultaneously, to allow more than one duct to open, or close simultaneously.
For example, in a system with a first duct that directs airflow to a first zone of the passenger compartment, and a second duct that directs airflow to a second zone of the passenger compartment, it can be desirable to use a single motor to simultaneously control individual doors within the two ducts to selectively block airflow through the two ducts. It can be desirable to operate the two doors such that they both open the same amount to allow the same amount of air to flow to both zones. By way of another example, a first duct may direct cool air toward the passenger compartment, while a second duct directs air through the heat exchanger before directing it toward the passenger compartment. In such a system, the temperature of the air directed toward the passenger compartment can depend on the relative amounts of air directed through the first and second ducts. It can be desirable to use a single motor to simultaneously control individual doors within the two ducts to selectively regulate airflow through each duct.
Current mechanisms for actuating multiple doors from a single motor generally include a linkage rod for coupling the operation of the two doors to the single motor. These linkage rods, are typically formed of a thermoplastic material to minimize weight and cost of the components. It has been found that the linkage rod can bend or flex during operation, which can lead to incomplete sealing of the doors, or undesirable differences in the door positions. Such bending can become more pronounced when the linkage rod becomes heated, such as due to the vehicle sitting in the sun on a hot day for example. Accordingly, there exists a need for a device that reliably and accurately articulates multiple HVAC duct doors with a single motor.